Flash lamp



June 13, 19 12.

J. A. M. VAN LIEMPT ETAL FLASH LAMP Filed Jan. 15, 1941 INVENTORS JOHANNES ANTONIUS MARIA VAN LIEMPT and PIE'TER LEIJDENS ATTONEY.

QQQN Qx- A] Patented June 13, 1944 assist FLASH LAMP Johannes Antonius Maria van Liempt and Pieter Leijdens, Eindhoven, Netherlands; vested in the Alien Property Custodian Application January 15, 1941, Serial No. 874,592 In the Netherlands December 16, 1939 6 Claims.

It is known to initiate the ignition oi flashlight material consisting oi comparatively thick aluminium wire, for instance of wire more than 35a in diameter, or of a comparatively thick aluminium foil having, for instance, a foil thickness of more than 1 by making use of a thin aluminimum wire having a thickness of 15 to 22; or again of a toll consisting of magnesium, aluminium or an alloy of these metals, which wire or foil has to be provided for this purpose as an intermediary material in the neighbourhood of the so-called ignition paste. In this manner "it is possible to obtain a long flash-time while maintaining the same time-lag of ignition occurring in a flash-light lamp in which the actinic eiiect is obtained by means of thin flash-light material. In the present case the term time-lag is to be understood to mean the time elapsing between switching-on the ignition current and the onset of the production of light. A long flash-time while retaining a short time-lag is important when such lamps are used with cameras comprising slit shutters which usually require a long time of travel of the slit.

The use of such intermediary ignition material in the form of foil having the required thickness, such as aluminium foil having a thickness of about 0.5;]. has the drawback that the material is diflicult to handle and when making use of thin aluminium wire having a diameter of about $0 to 22 the drawback is experienced that such a thin wire can be produced only by etching because drawing to such a thinness is technically unfeasible.

The present invention has for its object to obviate the said drawbacks concomitant with the use of the well-known intermediary ignition materials.

According to the invention this is achieved by means of a flash-light lamp whose gas-filled bulb contains a flash-light material in the form of a comparatively thick wire which is to be ignited secondarily, an actinic aluminium alloy adapted to be readily ignited in the form of a drawn wire of less than 45a in diameter which constitutes the intermediary ignition material, and an explosive primary ignition paste. a

In the present invention the secondary flashlight material in the form of a comparatively thick wire may consist either of aluminium or of an actinic aluminium alloy adapted to be readily ignited. In this connection flash-light material in the form of a comparatively thick wire is to be understood to mean wire having a diameter of min1um wires.

and to mean wire oi more than in diameter when it consists of the said aluminium alloy adapted to be readily ignited.

The invention therefore includes secondary flash-light material in the form of wire which as such is adapted to be ignited without the need for additional means and through a normal explosive ignition paste or not and then yields in itself a long flash time, but a much too long time lag for practical purposes.

According to one form of carrying the invention into effect the intermediary filamentary ignition material is advantageously mixed with the secondary filamentary flash-light material, so that the intermediary ignition material need not be located in the neighbourhood of the primary ignition paste, such as is necessary when making use of foil or of very thin extremely weak alu- In fact the filling of the bulb with the said actinic wire mixture can be readily efiected and, moreover, in one operation by resorting to the method disclosed in American patent specification 2,115,423, as a result of which the flash-light wire is distributed evenly or substantially evenly throughout the bulb contents which highly promotes the uniformity of the manufacture in regard to the light-time characteristic curve.

The invention may be used with particular advantage when the secondary flash-light material in the form of wire has such a thickness that in itself it can no longer-be ignited by a primary ignition paste, but only when making use at the same time of the intermediary ignition material according to the invention. v

As actinic aluminium alloys adapted to be readily ignited and suitable for the purposes of the invention we may mention, for instance; aluminium-magnesium alloys having a magnesium content of less than 13% or higher than 85%, aluminium-zinc-alloys having a zinc content of 20% at the most or aluminium-cadmium-alloys having a cadmium content of 80% at the most or mixtures of aluminium, cadmium and zinc having a zinc content of 20% at the most.

The term wire used in the present specification is to be understood to include also a flattened .wire or band whose width amounts to less than more than 35;:- when it consists of aluminium,

five times its thickness.

In order that the invention may be clearly understood and readily carried into efiect, we shall describe the same in more detail with reference to the accompanying drawing in which;

Figure 1 is a graph giving the characteristics of a flash lamp according to the prior art,

Fig. 2 is a graph giving the characteristics of a flash lamp according to the invention, and s Fig. 3 is a sectional view of the flash lamp according to the invention.

Fig. 1 shows the light-time characteristic curve of a. flash-light lamp having a bulb l5 mms. in diameter and filled with 100 mgs. of wire 50 metres inlength and 32a in diameter and consisting of an alloy oi. 93% Al and 7% Mg. The.

lamp has a filling of oxygen at a pressure of 40 cms.

Figure 2 represents the light-time characterlstic curve of a flash lamp according to the invention and as shown in Figure 3. With reference to Figure 3, the lamp shown therein has a bulb 6 of a diameter of 75 mms. which isfilled with a mixture of fine wire 8, which acts as the intermediate ignition material, and heavy wire 1, which acts as the secondary light-emitting element. The wire I has a weight of 65 mgs., a

diameter of 90p. and a length of 5.2 meters,';and

the wire 8 has a weight of 35 ms, a diameter of 32p. and a length of 17 meters. Wires 1 and 8 consist of an alloy of 93% Al and 7% Mg.

The lamp is provided with a filling or oxygen at a pressure 'of 40 cuts. and has an explosive ignition paste 9 provided on a filament Ill supported on the ends of two electric supply conductcrs ll. 1 I

The properties of the two flash-light lamps which, as has already been stated above,have bulbs of the same size and are in either case filled with 100 mgs. of flash-light material in the form of wire and with oxygen having a filling pressure of 40 cms., are summarised in the table below.

Flash-light lamp Bulb diameter 75 mm. 75 mm. Alloy 93% Al, 7% M g (100 mg.) 32 =50 m. (65 mg.) 90 ==l=4 lIl.

4.3Xl0 lum. 1.8Xl0 lum. 1.8)(10- see. 5.2Xl0- sec. 3.1)(10' sec. 7.6)(10- sec.

For making the table better understood it is to be noted that the terms:

What we claim is: Y

1. A flash lamp comprising a bulb, a gaseous filling, a quantity of comparatively thick wire within said bulb and acting as the secondary light-emitting element, a quantity of wire within the bulb and acting as an intermediate ignition 85% by weight of magnesium, an aluminum-zinc alloy containing not more than 20% zinc, an alu;

minum-cadmium alloy containingnot more than cadmium, and an aluminum-cadmim-zinc alloy containing not more than 20% zinc, and an explosive primary ignition paste for igniting said latter wire. 7

2. A flash lamp comprising a bulb, a gaseous filling, a quantity of comparatively thick wire within said bulb and acting as the secondary light-emitting element, a quantity of an aluminum-magnesium alloy wire within the bulb and acting as an intermediate ignition material, said aluminum-magnesium alloy being other than an aluminum-magnesium alloy containing 13% to by weight of magnesium, said aluminum-magnesium alloy wire having a diameter less than about 45 microns, and an explosive primary ignition paste for igniting said second wire.

3. Afiash lamp comprising a bulb, a gaseous filling a quantity of comparatively thick wire Within said bulb and acting as the-"secondary light-emitting element, a-quantity of a wire of an aluminum-zinc alloy containing not more than 20% zinc disposed within the bulb and acting as an intermediate ignition material, said latter wire having a diameter less than about 45 microns, and an explosive primary ignition paste for igniting said second wire.

4. A flash lamp comprising a bulb, a gaseous filling, a quantity of comparatively thick wire within said bulb and acting as the secondary light-emitting element, a quantity of a wire of an aluminum-cadmium alloy containing not more v than 80% cadmium disposed within the bulb and acting as an intermediate ignition material, said latter wire having a diameter less than about 45 microns, and an explosive primary ignition paste for igniting said second wire.

5. A flash lamp comprising a bulb, a gaseous filling, a quantity'of comparatively thick wire within said bulb and acting as the secondary light-emitting element, a quantity of a wire of an aluminum-cadmium-zinc mixture containing not more than 20% zinc disposed within the bulb and acting as an intermediate ignition material,

said latter wire having a diameter less than about 45 microns, and an explosive primary ignition paste for igniting said second wire.

6. A flash lamp comprising a bulb, a gaseous filling. a quantity of comparatively. thick wire within said bulb and acting as the secondary light-emitting element, a quantity of an aluminum-magnesium alloy wirewithin the, bulb and acting as an intermediate ignition material, said alloy wire consisting of about 93% aluminum and about 7% magnesium and having a diameter less than about 45 microns, and an explosive primary ignition paste for igniting said second wire.

JOHANNES ANTONIUS MARIA vim LIEMPT.

PIETER. LEIJDENS. i 

